1) Field of the Invention
The present invention relates to an information delivery and display system and an information delivery method.
2) Description of the Related Art
There has been an increase in the number of information delivery systems that display information such as electronic advertisements via a server on terminal devices with display features (hereinafter, “display terminal devices”). In such information delivery systems, however, it is necessary for the server to control or monitor the display terminal devices remotely.
In the conventional information delivery systems, remote control or remote-monitoring is carried out by the server sending to the terminal devices a control instruction and a monitor instruction by push connection rather than by the terminal devices actively fetching the control instruction and the monitor instruction from the server.
Further, there exists a method for checking for communication of information between the server and the display terminal device that involves determining by polling whether any event has occurred either from the server to the display terminal device or vice versa.
In the polling method disclosed in Japanese Patent Laid-Open Publication No. H1-192239, a polling timer is provided at each node connected to a mobile unit and polling is carried out from a key station to the mobile unit when the polling timer is timed out. The polling timer can be set according to the processing speed of each mobile unit, thus making it possible to schedule polling tailored to the mobile unit.
However, in the remote control and remote-monitoring of the display terminal device using the push connection, it is mandatory for the display terminal device to have a global internet provider (IP) in order for the server to send the control instruction and the monitor instruction to the display terminal device. Further, in the push connection, the server often uses a special port number to send the control instruction and the monitor instruction to the display terminal device, thus necessitating special firewall settings on the display terminal device. Again, in the push connection, the display terminal device must have a predetermined free port for receiving the control instruction and the monitor instruction from the server, thereby raising security issues.
Moreover, though it is possible in the conventional technology to set the polling timer according to the processing speed of the mobile unit, it is not possible to change the polling interval according to the status of the device to which information is delivered (the mobile unit) or the content of the information delivered.